I have a column that contains integers values for the number of documents.

select cast(cast(JOB_TOTAL_DOCS as char) as varchar(254)) docs...

When I try to cast the integer as char then to varchar.. the results would be concatenated into 1 character.

For example: if the original integer was 5691, after the cast the resulting varchar would be '5'. 753->'7', etc.

What am I doing wrong?

cast(JOB_TOTAL_DOCS as char) means:
cast(JOB_TOTAL_DOCS as char(1))

You need to specify the length yourself.